1. Field of the Invention
The present invention relates to a compound-eye imaging device having an optical imaging system which is formed of multiple micro optical systems so as to reduce the focal length, making it possible to reduce the thickness of the compound-eye imaging device.
2. Description of the Related Art
There has been developed a compound-eye imaging device as a thin camera module to be installed in a cellular phone, a personal computer, or the like. The compound-eye imaging device is mainly composed of: an optical lens array with multiple integrated optical lenses; a photodetector array for imaging multiple images formed by the respective optical lenses of the optical lens array; and an image reconstructing circuit for reconstructing the multiple images, imaged by the photodetector array, into one image by using parallax information between the multiple images.
It is known to form an image input unit by placing a light shielding block between the optical lens array and the photodetector array for partitioning a space between the optical lens array and the photodetector array into a matrix of spaces as seen on a plane perpendicular to the optical axis of each optical lens so as to prevent lights emitted from the optical lenses from interfering each other (refer to e.g. Japanese Laid-open Patent Publication 2001-61109). FIG. 10 is a schematic vertical cross-sectional view of a conventional compound-eye imaging device 100, showing a general structure of a conventional compound-eye imaging device. The structure of the conventional compound-eye imaging device 100 will be described with reference to FIG. 10.
The compound-eye imaging device 100 comprises: an optical lens array 104 with integrally formed multiple optical lenses 102; a stop member 111 for shielding unnecessary ambient light from entering the optical lenses 102; a photodetector array 106 placed at a predetermined distance from the optical lens array 104 for imaging multiple images respectively formed by the optical lenses 102; and a light shielding block 107 which is placed between the optical lens array 104 and the photodetector array 106, and which has a partition wall for partitioning a space between the optical lens array 104 and the photodetector array 106 into a matrix of spaces as seen on a plane perpendicular to an optical axis L of each optical lens 102 so as to prevent lights emitted from the respective optical lenses 102 from interfering each other. The optical lens array 104 is held by a lens holder 105. The shielding block 107 is formed of a plate-like or flat plate material having a predetermined thickness and having formed therein multiple light-passing holes H which face the respective optical lenses 102. In one way, laser processing is used to form such light-passing holes H in a metal plate. Otherwise, in some cases, a plate-like or flat plate material formed by a photo-curable resin may be used for the light shielding block 107.
In the conventional compound-eye imaging device 100, there is a problem in the quality of formed images. More specifically, as shown by a bent arrow A in FIG. 10, some of the lights emitted from the optical lenses 102, which are expected to directly arrive at the photodetector array 106, may first arrive at an inner wall surface Ha of a light-passing hole H, so as to be reflected by the inner wall surface Ha and then arrive at the photodetector array 106. Because of the existence of both the direct and reflected lights from the optical lenses 102, there is a risk of occurrence of ghost or flare in an image formed by the photodetector array 106.